The present invention concerns a seal for hydraulically sealing a piston rod. Piston-rod seals of this genus are preferably employed to seal the projecting end of an oscillating piston rod in a hydraulic dashpot. The hydraulic fluid is highly compressed and must be effectively contained without resulting in excess friction between the piston rod and the seal.
German 8 201 327 U1 discloses a piston-rod seal of this genus. The device has a drawback, however, in that it can be effective at low temperatures only if it is provided with a sealing component that rests against an elastomeric component and is powerfully forced into position at high temperatures. The result is considerable friction and inefficient operation on the part of the piston rod.
The object of the present invention is accordingly a piston-rod seal of the aforesaid genus improved to the extent that it will effectively prevent the leakage of hydraulic fluid at low temperatures while subjecting the sealing component to as little force as possible at high temperatures.
The major advantage of the present invention is that the elastomeric component is specifically designed to force the sealing component against the piston rod to an extent that depends on the prevailing temperature.